Directional drilling is a useful technique for several procedures such as utility installation, etc. One common type of directional drilling is horizontal directional drilling, where a drill stem is extended essentially horizontally to form passages under structures such as roads for example. Drill heads in directional drilling typically have a feature which causes the drill head to steer in one direction when forced ahead by a drilling device. During a boring operation, pressure is applied through a drill stem from behind to the drill head. During a straight bore, the drill stem is typically rotated at a regular rate so that on average, only straight ahead drilling is accomplished. In order to steer a drill head, the rotation is temporarily stopped, and the drill head is allowed to steer in the desired direction. Once the steering maneuver is complete, the drill head is again rotated at a regular rate for straight ahead drilling.
There are numerous types of ground and soil conditions that affect performance of drill heads. As a result, there are numerous designs of drill heads to match each ground type. One difficult type of ground includes tightly packed and dry gravelly soil. One example of this type of ground can be found in southern California. This type of ground is difficult because current drill head designs do not make sufficient forward progress to turn the drill stem when they are not being rotated. This makes steering in such conditions difficult. Although this ground type is used as an example, embodiments of the following invention are not limited to use in such conditions.
What is needed is a drill head and drill assembly with improved steering and improved performance under various ground conditions including, but not limited to dry tightly packed soil.